Forgive us if we stray onto the subject of the Olympics for a moment. Many of you may be getting a bit jaded of them already.

However we just want to focus one aspect of them - ministers and organisers of the games are desperate to ensure that they are not disrupted by protesters. It seems likely that police chiefs will be frantically seeking at this time any intelligence about protests which are being planned by campaigners. It is probably fair to say that intelligence from undercover officers or informants will be at a premium at the moment.

Many would not find it surprising if in the days running up to the Olympics or during the Games, there is a re-run of the wave of arrests which were made by police just before last year's Royal Wedding.

The High Court judges dismissed their case and in effect endorsed police tactics of pre-emptive arrests - a ruling which strengthens of the hand of the police if they do start arresting campaigners they say are about to disrupt the Olympics.

Last week's High Court ruling gives a few glimpses of the intelligence which was used to arrest or search the activists before the Royal Wedding. It is of course difficult to know where this intelligence came from - it may be a simple matter of police reading websites or leaflets advertising a protest, or it may have originated directly or indirectly from undercover officers.

Worth looking at is the case of the pair (Theodora Middleton and Dafydd Lewis) who lived at the environmental camp at Heathrow. The camp, known as Grow Heathrow, was set up in what was a derelict site two years ago, with the aim of turning the area into a market garden for the local community and to highlight the environmental damage that would be caused if the airport was expanded.

The day before the Royal Wedding, police searched the camp on a warrant which said :"Intelligence provides that Sipson Camp, located at Sipson Village, West Drayton, Middlesex is occupied by activists affiliated to environmental and extreme left wing groups.

"Intelligence further provides that paint bombs may have been moved to the Sipson Camp for storage which may be utilized for criminal damage.

"Intelligence also provides that individuals who may wish to disrupt the Royal wedding are also resident at the camp."

As it turned out, the intelligence was wrong, as nothing was found during the search of the camp. Who provided the intelligence - an informant or undercover officer, for instance - is not known because the police, as they routinely do, got a gagging order (or in official parlance, a public interest immunity claim) to protect the source.

As the Guardian reported here, "in the months leading up to the wedding, a series of demonstrations by students, trade unionists and others saw hundreds of thousands of people take to the streets to protest against government cuts. There were outbreaks of disorder and in one case student demonstrators attacked a car carrying Prince Charles and his wife Camilla. Senior police chiefs said at the time they were planning to take pre-emptive action to ensure there was no repeat of the trouble. Lynne Owens, then assistant commissioner at the Met, told journalists: "We have both overt and covert policing activities ongoing and we will prevent people coming to London to cause criminal behaviour if that is their intention"."